Gut flora alterations due to lipopolysaccharide derived from Porphyromonas gingivalis.

Gut dysbiosis induces 'leaky gut,' a condition associated with diabetes, NASH, and various auto-immune diseases. Porphyromonas gingivalis is a periodontopathic bacterium which causes periodontal tissue breakdown, and often enters the systemic blood flow. Oral administration of P. gingivalis induced gut dysbiosis in mice model, but no systemic administration of P. gingivalis has been reported thus far. In the present study, we investigated the effect of P. gingivalis-derived lipopolysaccharide (Pg-LPS) on the intestinal flora of our established mouse model. Eight-week-old C57BL/6J mice were intraperitoneally administered Pg-LPS. Three months later, DNA was extracted from stool, and RNA from the small and large intestines. After euthanizing the mice, pathological sections of the intestinal tract were prepared and stained with hematoxylin and eosin (H&E). Tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, and IL-6 expression levels were evaluated using quantitative PCR. 16S rRNA gene PCR amplicon analysis data were acquired using NGS. Microbial diversity and composition were analyzed using Quantitative Insights into Microbial Ecology 2. Furthermore, alterations in microbial function were performed by PICRUSt2. No significant inflammatory changes were observed in the H&E. No significant differences in the mRNA levels of IL-1β, IL-6, and TNF-α were observed between the groups. Pg-LPS administration decreased the abundance of Allobacterium in the gut. A predictive metagenomic analysis by PICRUSt2 and STAMP showed that 47 pathways increased and 17 pathways decreased after Pg-LPS administration. Systemic application of periodontal pathogens may cause changes in the intestinal flora which may affect the physiological functions of the intestinal tract.